Setting up postfix-policyd (1.82-2) ...dbconfig-common: writing config to /etc/dbconfig-common/postfix-policyd.conf*** WARNING: ucf was run from a maintainer script that uses debconf, but the script did not pass --debconf-ok to ucf. The maintainer script should be fixed to not stop debconf before calling ucf, and pass it this parameter. For now, ucf will revert to using old-style, non-debconf prompting. Ugh!

I had the same error messages myself. Note I also had a number of modules already installed. I had PHP-LDAP admin and PHP-MYSQL installed, and can't access either of them after I ran the iredmail script.